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Protein

F-BAR domain only protein 1

Gene

FCHO1

Organism
Homo sapiens (Human)
Status
Reviewed-Annotation score: Annotation score: 5 out of 5-Experimental evidence at protein leveli

Functioni

Functions in an early step of clathrin-mediated endocytosis. Has both a membrane binding/bending activity and the ability to recruit proteins essential to the formation of functional clathrin-coated pits. May regulate Bmp signaling by regulating clathrin-mediated endocytosis of Bmp receptors.1 Publication

GO - Molecular functioni

  1. AP-2 adaptor complex binding Source: MGI

GO - Biological processi

  1. clathrin coat assembly Source: UniProtKB
  2. clathrin-mediated endocytosis Source: UniProtKB
Complete GO annotation...

Keywords - Biological processi

Endocytosis

Names & Taxonomyi

Protein namesi
Recommended name:
F-BAR domain only protein 1
Gene namesi
Name:FCHO1
Synonyms:KIAA0290
OrganismiHomo sapiens (Human)
Taxonomic identifieri9606 [NCBI]
Taxonomic lineageiEukaryotaMetazoaChordataCraniataVertebrataEuteleostomiMammaliaEutheriaEuarchontogliresPrimatesHaplorrhiniCatarrhiniHominidaeHomo
ProteomesiUP000005640 Componenti: Chromosome 19

Organism-specific databases

HGNCiHGNC:29002. FCHO1.

Subcellular locationi

Membraneclathrin-coated pit 2 Publications; Peripheral membrane protein 2 Publications; Cytoplasmic side 2 Publications
Note: Associated with forming but not mature clathrin-coated vesicles. The recruitment to coated-pits precede the one of clathrin and the adaptor protein complex AP-2. According to PubMed:17617719 it may also dynamically associate with Golgi/TGN membranes.

GO - Cellular componenti

  1. coated pit Source: UniProtKB
  2. plasma membrane Source: UniProtKB
Complete GO annotation...

Keywords - Cellular componenti

Coated pit, Membrane

Pathology & Biotechi

Organism-specific databases

PharmGKBiPA134870625.

PTM / Processingi

Molecule processing

Feature keyPosition(s)LengthDescriptionGraphical viewFeature identifierActions
Chaini1 – 889889F-BAR domain only protein 1PRO_0000271759Add
BLAST

Amino acid modifications

Feature keyPosition(s)LengthDescriptionGraphical viewFeature identifierActions
Modified residuei616 – 6161Phosphoserine1 Publication

Keywords - PTMi

Phosphoprotein

Proteomic databases

MaxQBiO14526.
PaxDbiO14526.
PRIDEiO14526.

PTM databases

PhosphoSiteiO14526.

Expressioni

Gene expression databases

BgeeiO14526.
CleanExiHS_FCHO1.
ExpressionAtlasiO14526. baseline and differential.
GenevestigatoriO14526.

Organism-specific databases

HPAiHPA041653.

Interactioni

Subunit structurei

May oligomerize and form homotetramer (By similarity). Interacts with AP2A2 and AP2B1; 2 subunits of the adaptor protein complex AP-2. Interacts with DAB2. Interacts with clathrin (CLTC or CLTCL1). Interacts with EPS15, EPS15R and ITSN1. Interacts with AGFG1 and CALM. May interact with ACVR1; linking this receptor to clathrin-mediated endocytosis.By similarity1 Publication

Binary interactionsi

WithEntry#Exp.IntActNotes
A7BFV92EBI-719823,EBI-6095043From a different organism.

Protein-protein interaction databases

BioGridi116764. 8 interactions.
IntActiO14526. 4 interactions.
MINTiMINT-7979234.
STRINGi9606.ENSP00000252771.

Structurei

3D structure databases

ProteinModelPortaliO14526.
SMRiO14526. Positions 1-269.
ModBaseiSearch...
MobiDBiSearch...

Family & Domainsi

Domains and Repeats

Feature keyPosition(s)LengthDescriptionGraphical viewFeature identifierActions
Domaini1 – 248248F-BARPROSITE-ProRule annotationAdd
BLAST
Domaini625 – 888264MHDPROSITE-ProRule annotationAdd
BLAST

Region

Feature keyPosition(s)LengthDescriptionGraphical viewFeature identifierActions
Regioni1 – 275275Mediates membrane-bindingAdd
BLAST
Regioni267 – 442176Mediates interaction with the adaptor protein complex AP-2Add
BLAST
Regioni609 – 889281Mediates interaction with AGFG1, CALM, DAB2, EPS15, EPS15R, ITSN1 and clathrinAdd
BLAST

Coiled coil

Feature keyPosition(s)LengthDescriptionGraphical viewFeature identifierActions
Coiled coili156 – 19540Sequence AnalysisAdd
BLAST

Compositional bias

Feature keyPosition(s)LengthDescriptionGraphical viewFeature identifierActions
Compositional biasi375 – 3784Poly-Ala
Compositional biasi465 – 4684Poly-Ser
Compositional biasi480 – 56182Pro-richAdd
BLAST
Compositional biasi671 – 6744Poly-Pro

Sequence similaritiesi

Belongs to the FCHO family.Curated
Contains 1 F-BAR domain.PROSITE-ProRule annotation
Contains 1 MHD (mu homology) domain.PROSITE-ProRule annotation

Keywords - Domaini

Coiled coil

Phylogenomic databases

eggNOGiNOG324072.
GeneTreeiENSGT00510000046419.
HOGENOMiHOG000231544.
HOVERGENiHBG081524.
InParanoidiO14526.
OrthoDBiEOG712TVK.
PhylomeDBiO14526.
TreeFamiTF328986.

Family and domain databases

InterProiIPR001060. FCH_dom.
IPR030121. FCHo1.
IPR028565. MHD.
IPR018808. Muniscin_C.
[Graphical view]
PANTHERiPTHR23065:SF6. PTHR23065:SF6. 1 hit.
PfamiPF00611. FCH. 1 hit.
PF10291. muHD. 1 hit.
[Graphical view]
SMARTiSM00055. FCH. 1 hit.
[Graphical view]
PROSITEiPS51741. F_BAR. 1 hit.
PS51072. MHD. 1 hit.
[Graphical view]

Sequences (3)i

Sequence statusi: Complete.

This entry describes 3 isoformsi produced by alternative splicing. AlignAdd to basket

Isoform 1 (identifier: O14526-1) [UniParc]FASTAAdd to basket

This isoform has been chosen as the 'canonical' sequence. All positional information in this entry refers to it. This is also the sequence that appears in the downloadable versions of the entry.

« Hide

        10         20         30         40         50
MSYFGEHFWG EKNHGFEVLY HSVKQGPIST KELADFIRER ATIEETYSKA
60 70 80 90 100
MAKLSKLASN GTPMGTFAPL WEVFRVSSDK LALCHLELTR KLQDLIKDVL
110 120 130 140 150
RYGEEQLKTH KKCKEEVVST LDAVQVLSGV SQLLPKSREN YLNRCMDQER
160 170 180 190 200
LRRESTSQKE MDKAETKTKK AAESLRRSVE KYNSARADFE QKMLDSALRF
210 220 230 240 250
QAMEETHLRH MKALLGSYAH SVEDTHVQIG QVHEEFKQNI ENVSVEMLLR
260 270 280 290 300
KFAESKGTGR EKPGPLDFEA YSAAALQEAM KRLRGAKAFR LPGLSRRERE
310 320 330 340 350
PEPPAAVDFL EPDSGTCPEV DEEGFTVRPD VTQNSTAEPS RFSSSDSDFD
360 370 380 390 400
DEEPRKFYVH IKPAPARAPA CSPEAAAAQL RATAGSLILP PGPGGTMKRH
410 420 430 440 450
SSRDAAGKPQ RPRSAPRTSS CAERLQSEEQ VSKNLFGPPL ESAFDHEDFT
460 470 480 490 500
GSSSLGFTSS PSPFSSSSPE NVEDSGLDSP SHAAPGPSPD SWVPRPGTPQ
510 520 530 540 550
SPPSCRAPPP EARGIRAPPL PDSPQPLASS PGPWGLEALA GGDLMPAPAD
560 570 580 590 600
PTAREGLAAP PRRLRSRKVS CPLTRSNGDL SRSLSPSPLG SSAASTALER
610 620 630 640 650
PSFLSQTGHG VSRGPSPVVL GSQDALPIAT AFTEYVHAYF RGHSPSCLAR
660 670 680 690 700
VTGELTMTFP AGIVRVFSGT PPPPVLSFRL VHTTAIEHFQ PNADLLFSDP
710 720 730 740 750
SQSDPETKDF WLNMAALTEA LQRQAEQNPT ASYYNVVLLR YQFSRPGPQS
760 770 780 790 800
VPLQLSAHWQ CGATLTQVSV EYGYRPGATA VPTPLTNVQI LLPVGEPVTN
810 820 830 840 850
VRLQPAATWN LEEKRLTWRL PDVSEAGGSG RLSASWEPLS GPSTPSPVAA
860 870 880
QFTSEGTTLS GVDLELVGSG YRMSLVKRRF ATGMYLVSC
Length:889
Mass (Da):96,861
Last modified:January 8, 2007 - v2
Checksum:i8CDA1F24F42256D2
GO
Isoform 2 (identifier: O14526-2) [UniParc]FASTAAdd to basket

The sequence of this isoform differs from the canonical sequence as follows:
     883-889: GMYLVSC → AAPPQG

Note: No experimental confirmation available.

Show »
Length:888
Mass (Da):96,629
Checksum:i27DB24B8191372A9
GO
Isoform 3 (identifier: O14526-3) [UniParc]FASTAAdd to basket

The sequence of this isoform differs from the canonical sequence as follows:
     1-50: Missing.

Note: No experimental confirmation available.

Show »
Length:839
Mass (Da):91,013
Checksum:i4CC94A2046D108CE
GO

Sequence cautioni

The sequence BAA22959.1 differs from that shown. Reason: Erroneous initiation. Curated

Alternative sequence

Feature keyPosition(s)LengthDescriptionGraphical viewFeature identifierActions
Alternative sequencei1 – 5050Missing in isoform 3. 1 PublicationVSP_046906Add
BLAST
Alternative sequencei883 – 8897GMYLVSC → AAPPQG in isoform 2. 1 PublicationVSP_022338

Sequence databases

Select the link destinations:
EMBLi
GenBanki
DDBJi
Links Updated
AB006628 mRNA. Translation: BAA22959.1. Different initiation.
AK291410 mRNA. Translation: BAF84099.1.
AK303623 mRNA. Translation: BAG64632.1.
AC008761 Genomic DNA. No translation available.
CH471106 Genomic DNA. Translation: EAW84629.1.
BC028021 mRNA. Translation: AAH28021.1.
BC041130 mRNA. Translation: AAH41130.1.
CCDSiCCDS32955.1. [O14526-1]
CCDS59366.1. [O14526-3]
PIRiT00039.
RefSeqiNP_001154829.1. NM_001161357.1.
NP_001154830.1. NM_001161358.1. [O14526-1]
NP_001154831.1. NM_001161359.1. [O14526-3]
NP_055937.1. NM_015122.2. [O14526-1]
XP_006722764.1. XM_006722701.1. [O14526-1]
XP_006722765.1. XM_006722702.1. [O14526-1]
UniGeneiHs.96485.

Genome annotation databases

EnsembliENST00000252771; ENSP00000252771; ENSG00000130475. [O14526-1]
ENST00000595033; ENSP00000472668; ENSG00000130475. [O14526-3]
ENST00000596536; ENSP00000470731; ENSG00000130475. [O14526-1]
ENST00000596951; ENSP00000472417; ENSG00000130475. [O14526-1]
ENST00000600676; ENSP00000470493; ENSG00000130475. [O14526-1]
GeneIDi23149.
KEGGihsa:23149.
UCSCiuc002nhg.3. human. [O14526-2]
uc002nhh.2. human. [O14526-1]

Keywords - Coding sequence diversityi

Alternative splicing

Cross-referencesi

Sequence databases

Select the link destinations:
EMBLi
GenBanki
DDBJi
Links Updated
AB006628 mRNA. Translation: BAA22959.1. Different initiation.
AK291410 mRNA. Translation: BAF84099.1.
AK303623 mRNA. Translation: BAG64632.1.
AC008761 Genomic DNA. No translation available.
CH471106 Genomic DNA. Translation: EAW84629.1.
BC028021 mRNA. Translation: AAH28021.1.
BC041130 mRNA. Translation: AAH41130.1.
CCDSiCCDS32955.1. [O14526-1]
CCDS59366.1. [O14526-3]
PIRiT00039.
RefSeqiNP_001154829.1. NM_001161357.1.
NP_001154830.1. NM_001161358.1. [O14526-1]
NP_001154831.1. NM_001161359.1. [O14526-3]
NP_055937.1. NM_015122.2. [O14526-1]
XP_006722764.1. XM_006722701.1. [O14526-1]
XP_006722765.1. XM_006722702.1. [O14526-1]
UniGeneiHs.96485.

3D structure databases

ProteinModelPortaliO14526.
SMRiO14526. Positions 1-269.
ModBaseiSearch...
MobiDBiSearch...

Protein-protein interaction databases

BioGridi116764. 8 interactions.
IntActiO14526. 4 interactions.
MINTiMINT-7979234.
STRINGi9606.ENSP00000252771.

PTM databases

PhosphoSiteiO14526.

Proteomic databases

MaxQBiO14526.
PaxDbiO14526.
PRIDEiO14526.

Protocols and materials databases

Structural Biology KnowledgebaseSearch...

Genome annotation databases

EnsembliENST00000252771; ENSP00000252771; ENSG00000130475. [O14526-1]
ENST00000595033; ENSP00000472668; ENSG00000130475. [O14526-3]
ENST00000596536; ENSP00000470731; ENSG00000130475. [O14526-1]
ENST00000596951; ENSP00000472417; ENSG00000130475. [O14526-1]
ENST00000600676; ENSP00000470493; ENSG00000130475. [O14526-1]
GeneIDi23149.
KEGGihsa:23149.
UCSCiuc002nhg.3. human. [O14526-2]
uc002nhh.2. human. [O14526-1]

Organism-specific databases

CTDi23149.
GeneCardsiGC19P017956.
HGNCiHGNC:29002. FCHO1.
HPAiHPA041653.
MIMi613437. gene.
neXtProtiNX_O14526.
PharmGKBiPA134870625.
HUGEiSearch...
GenAtlasiSearch...

Phylogenomic databases

eggNOGiNOG324072.
GeneTreeiENSGT00510000046419.
HOGENOMiHOG000231544.
HOVERGENiHBG081524.
InParanoidiO14526.
OrthoDBiEOG712TVK.
PhylomeDBiO14526.
TreeFamiTF328986.

Miscellaneous databases

ChiTaRSiFCHO1. human.
GenomeRNAii23149.
NextBioi44466.
PROiO14526.
SOURCEiSearch...

Gene expression databases

BgeeiO14526.
CleanExiHS_FCHO1.
ExpressionAtlasiO14526. baseline and differential.
GenevestigatoriO14526.

Family and domain databases

InterProiIPR001060. FCH_dom.
IPR030121. FCHo1.
IPR028565. MHD.
IPR018808. Muniscin_C.
[Graphical view]
PANTHERiPTHR23065:SF6. PTHR23065:SF6. 1 hit.
PfamiPF00611. FCH. 1 hit.
PF10291. muHD. 1 hit.
[Graphical view]
SMARTiSM00055. FCH. 1 hit.
[Graphical view]
PROSITEiPS51741. F_BAR. 1 hit.
PS51072. MHD. 1 hit.
[Graphical view]
ProtoNetiSearch...

Publicationsi

« Hide 'large scale' publications
  1. "Construction and characterization of human brain cDNA libraries suitable for analysis of cDNA clones encoding relatively large proteins."
    Ohara O., Nagase T., Ishikawa K., Nakajima D., Ohira M., Seki N., Nomura N.
    DNA Res. 4:53-59(1996) [PubMed] [Europe PMC] [Abstract]
    Cited for: NUCLEOTIDE SEQUENCE [LARGE SCALE MRNA] (ISOFORM 1).
    Tissue: Brain.
  2. "Complete sequencing and characterization of 21,243 full-length human cDNAs."
    Ota T., Suzuki Y., Nishikawa T., Otsuki T., Sugiyama T., Irie R., Wakamatsu A., Hayashi K., Sato H., Nagai K., Kimura K., Makita H., Sekine M., Obayashi M., Nishi T., Shibahara T., Tanaka T., Ishii S.
    , Yamamoto J., Saito K., Kawai Y., Isono Y., Nakamura Y., Nagahari K., Murakami K., Yasuda T., Iwayanagi T., Wagatsuma M., Shiratori A., Sudo H., Hosoiri T., Kaku Y., Kodaira H., Kondo H., Sugawara M., Takahashi M., Kanda K., Yokoi T., Furuya T., Kikkawa E., Omura Y., Abe K., Kamihara K., Katsuta N., Sato K., Tanikawa M., Yamazaki M., Ninomiya K., Ishibashi T., Yamashita H., Murakawa K., Fujimori K., Tanai H., Kimata M., Watanabe M., Hiraoka S., Chiba Y., Ishida S., Ono Y., Takiguchi S., Watanabe S., Yosida M., Hotuta T., Kusano J., Kanehori K., Takahashi-Fujii A., Hara H., Tanase T.-O., Nomura Y., Togiya S., Komai F., Hara R., Takeuchi K., Arita M., Imose N., Musashino K., Yuuki H., Oshima A., Sasaki N., Aotsuka S., Yoshikawa Y., Matsunawa H., Ichihara T., Shiohata N., Sano S., Moriya S., Momiyama H., Satoh N., Takami S., Terashima Y., Suzuki O., Nakagawa S., Senoh A., Mizoguchi H., Goto Y., Shimizu F., Wakebe H., Hishigaki H., Watanabe T., Sugiyama A., Takemoto M., Kawakami B., Yamazaki M., Watanabe K., Kumagai A., Itakura S., Fukuzumi Y., Fujimori Y., Komiyama M., Tashiro H., Tanigami A., Fujiwara T., Ono T., Yamada K., Fujii Y., Ozaki K., Hirao M., Ohmori Y., Kawabata A., Hikiji T., Kobatake N., Inagaki H., Ikema Y., Okamoto S., Okitani R., Kawakami T., Noguchi S., Itoh T., Shigeta K., Senba T., Matsumura K., Nakajima Y., Mizuno T., Morinaga M., Sasaki M., Togashi T., Oyama M., Hata H., Watanabe M., Komatsu T., Mizushima-Sugano J., Satoh T., Shirai Y., Takahashi Y., Nakagawa K., Okumura K., Nagase T., Nomura N., Kikuchi H., Masuho Y., Yamashita R., Nakai K., Yada T., Nakamura Y., Ohara O., Isogai T., Sugano S.
    Nat. Genet. 36:40-45(2003) [PubMed] [Europe PMC] [Abstract]
    Cited for: NUCLEOTIDE SEQUENCE [LARGE SCALE MRNA] (ISOFORMS 1 AND 3).
    Tissue: Brain and Thymus.
  3. "The DNA sequence and biology of human chromosome 19."
    Grimwood J., Gordon L.A., Olsen A.S., Terry A., Schmutz J., Lamerdin J.E., Hellsten U., Goodstein D., Couronne O., Tran-Gyamfi M., Aerts A., Altherr M., Ashworth L., Bajorek E., Black S., Branscomb E., Caenepeel S., Carrano A.V.
    , Caoile C., Chan Y.M., Christensen M., Cleland C.A., Copeland A., Dalin E., Dehal P., Denys M., Detter J.C., Escobar J., Flowers D., Fotopulos D., Garcia C., Georgescu A.M., Glavina T., Gomez M., Gonzales E., Groza M., Hammon N., Hawkins T., Haydu L., Ho I., Huang W., Israni S., Jett J., Kadner K., Kimball H., Kobayashi A., Larionov V., Leem S.-H., Lopez F., Lou Y., Lowry S., Malfatti S., Martinez D., McCready P.M., Medina C., Morgan J., Nelson K., Nolan M., Ovcharenko I., Pitluck S., Pollard M., Popkie A.P., Predki P., Quan G., Ramirez L., Rash S., Retterer J., Rodriguez A., Rogers S., Salamov A., Salazar A., She X., Smith D., Slezak T., Solovyev V., Thayer N., Tice H., Tsai M., Ustaszewska A., Vo N., Wagner M., Wheeler J., Wu K., Xie G., Yang J., Dubchak I., Furey T.S., DeJong P., Dickson M., Gordon D., Eichler E.E., Pennacchio L.A., Richardson P., Stubbs L., Rokhsar D.S., Myers R.M., Rubin E.M., Lucas S.M.
    Nature 428:529-535(2003) [PubMed] [Europe PMC] [Abstract]
    Cited for: NUCLEOTIDE SEQUENCE [LARGE SCALE GENOMIC DNA].
  4. Cited for: NUCLEOTIDE SEQUENCE [LARGE SCALE GENOMIC DNA].
  5. "The status, quality, and expansion of the NIH full-length cDNA project: the Mammalian Gene Collection (MGC)."
    The MGC Project Team
    Genome Res. 14:2121-2127(2003) [PubMed] [Europe PMC] [Abstract]
    Cited for: NUCLEOTIDE SEQUENCE [LARGE SCALE MRNA] (ISOFORMS 1 AND 2).
    Tissue: Blood.
  6. "Dynamic behavior of FCHO1 revealed by live-cell imaging microscopy: its possible involvement in clathrin-coated vesicle formation."
    Sakaushi S., Inoue K., Zushi H., Senda-Murata K., Fukada T., Oka S., Sugimoto K.
    Biosci. Biotechnol. Biochem. 71:1764-1768(2006) [PubMed] [Europe PMC] [Abstract]
    Cited for: SUBCELLULAR LOCATION.
  7. "Quantitative phosphoproteomic analysis of T cell receptor signaling reveals system-wide modulation of protein-protein interactions."
    Mayya V., Lundgren D.H., Hwang S.-I., Rezaul K., Wu L., Eng J.K., Rodionov V., Han D.K.
    Sci. Signal. 2:RA46-RA46(2008) [PubMed] [Europe PMC] [Abstract]
    Cited for: PHOSPHORYLATION [LARGE SCALE ANALYSIS] AT SER-616, IDENTIFICATION BY MASS SPECTROMETRY [LARGE SCALE ANALYSIS].
    Tissue: Leukemic T-cell.
  8. "FCHo proteins are nucleators of clathrin-mediated endocytosis."
    Henne W.M., Boucrot E., Meinecke M., Evergren E., Vallis Y., Mittal R., McMahon H.T.
    Science 328:1281-1284(2009) [PubMed] [Europe PMC] [Abstract]
    Cited for: FUNCTION IN CLATHRIN-COATED PITS NUCLEATION, SUBCELLULAR LOCATION.
  9. "Distinct and separable activities of the endocytic clathrin-coat components Fcho1/2 and AP-2 in developmental patterning."
    Umasankar P.K., Sanker S., Thieman J.R., Chakraborty S., Wendland B., Tsang M., Traub L.M.
    Nat. Cell Biol. 14:488-501(2011) [PubMed] [Europe PMC] [Abstract]
    Cited for: LIPID-BINDING, INTERACTION WITH ACVR1; AGFG1; AP2A2; AP2B1; CALM; DAB2; EPS15; EPS15R; ITSN1 AND CLATHRIN.

Entry informationi

Entry nameiFCHO1_HUMAN
AccessioniPrimary (citable) accession number: O14526
Secondary accession number(s): A6NHE6
, A8K5U5, B4E120, Q05C93, Q8IW22
Entry historyi
Integrated into UniProtKB/Swiss-Prot: January 8, 2007
Last sequence update: January 8, 2007
Last modified: March 3, 2015
This is version 103 of the entry and version 2 of the sequence. [Complete history]
Entry statusiReviewed (UniProtKB/Swiss-Prot)
Annotation programChordata Protein Annotation Program
DisclaimerAny medical or genetic information present in this entry is provided for research, educational and informational purposes only. It is not in any way intended to be used as a substitute for professional medical advice, diagnosis, treatment or care.

Miscellaneousi

Keywords - Technical termi

Complete proteome, Reference proteome

Documents

  1. Human chromosome 19
    Human chromosome 19: entries, gene names and cross-references to MIM
  2. MIM cross-references
    Online Mendelian Inheritance in Man (MIM) cross-references in UniProtKB/Swiss-Prot
  3. SIMILARITY comments
    Index of protein domains and families

External Data

Dasty 3

Similar proteinsi

Links to similar proteins from the UniProt Reference Clusters (UniRef) at 100%, 90% and 50% sequence identity:
100%UniRef100 combines identical sequences and sub-fragments with 11 or more residues from any organism into Uniref entry.
90%UniRef90 is built by clustering UniRef100 sequences that have at least 90% sequence identity to, and 80% overlap with, the longest sequence (a.k.a seed sequence).
50%UniRef50 is built by clustering UniRef90 seed sequences that have at least 50% sequence identity to, and 80% overlap with, the longest sequence in the cluster.